Tektronix 585 - Page 53

Maintenance — Type 585
normal, the trouble can be: open signal connections, no
signal source, the plug-in, the probe, or even loose c rt con
nections.
The material that follows contains information for trouble 
shooting each circuit for various types of troubles. A method
is described, in some instances, for locating the stage in
which the trouble may be originating; once the stage at
fault is known, the component(s) causing the trouble can be
located by voltage and resistance measurements or by sub 
stitution. In certain other instances the information is more
specific and the trouble can be traced to a particular com 
ponent.
Front-Panel Checks
The following front-panel checks will help you to isolate
the trouble in an instrument to a given circuit. However, the
interrelation between circuits is such that it is not always
possible to isolate the trouble exactly using these checks.
If you are unfamiliar with the instrument, these front-panel
checks should prove helpful in looking for the trouble.
Before attempting any of the following front-panel checks
make sure that the plug-in installed in the instrument is
operating correctly. If the pilot lamp fails to light when the
POWER switch is turned to the ON position, and if the
fan fails to operate, turn to the section on troubleshooting
the Low-Voltage Power Supply. If the pilot light and fan
operate but the Time-Delay Relay fails to operate with an
audible “ click" in less than one minute, you should also
consult the section on Troubleshooting the Low-Voltage
Power Supply.
With a Type 84 Plug-In Test Unit installed, and the pilot
light and fan both operating, allow the oscilloscope to run
for several minutes.
Set the front-panel controls as follows:
A' STABILITY
'A' TRIGGERING LEVEL
fully clockwise
0
'A' TRIGGERING SOURCE
INT.
A' TRIGGER SLOPE
+
A ’ TIME/CM
5 MILLISEC
'A' VARIABLE (TIME/CM)
fully clockwise
HORIZONTAL DISPLAY
A
B' STABILITY
counterclockwise, but
not PRESET
FOCUS
mid-range
INTENSITY
fully counterclockwise
ASTIGMATISM
mid-range
SCALE ILLUMINATION
mid-range
HORIZONTAL POSITION
mid-range
VERNIER
mid-range
Other controls may be left at any setting.
Set the Type 84 front-panel controls as follows:
LOAD NORM.
DISPLAY SELECTOR CAL. (2 CM) AND
ALT. SYNC
VERTICAL POSITION mid-range
Other Type 84 controls may be left at any setting.
With the Type 84 controls as above, there should be two
traces, two centimeters apart on the c rt. It may be neces 
sary to readjust the VERTICAL POSITION control to bring
both traces in view.
Fig. 5-10. Location of power supply test points underneath the
scope.
Fig. 5-11. Calibrator and power supply test points.
5-7